Use of selected, biologically safe stabilizers in polyvinyl-ester-based impregnating compositions for soil stabilization

ABSTRACT

The invention relates to the use of fatty acids or fatty alcohols--which are solid at room temperature and/or which cure in the presence of air--and/or at least substantially water-insoluble esters, ethers and/or salts thereof with, in particular, polyvalent cations as degradable and biologically safe stabilizers for increasing the water resistance of soil impregnations based on polyvinyl esters, more particularly PVAc.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improvement in and extension of theteaching described in earlier German patent application P 43 24 474.2for the surface stabilization of sand and/or soil, hereinafter generallyreferred to as soil. This earlier application describes a modificationto the process known per se of achieving at least temporarystabilization by application and introduction of aqueous polymerdispersions to and into surface layers of soil. The water in theimpregnating composition introduced dries in a comparatively short timeand the polymer phase remaining behind solidifies the structure, forexample the granular structure, of the impregnated soil without undulyaffecting the permeability of these layers to water. Surfacestabilization such as this is not confined to soil in the narrowersense. The corresponding stabilization of other surface zones which haveto be protected, for example, against wind erosion falls within thescope of the teaching according to the invention. Examples of suchsurface zones include dumps and/or spoil banks with or withoutapplication of a covering of top soil or other protective layers.

2. Discussion of Related Art

Development and practice have been concerned for decades with theconcept--on which the present invention is also based--of applyingsynthetic polymers which cause particulate solids to adhere to oneanother to the surfaces to be stabilized in the form of aqueousdispersions or emulsions and leaving them to dry thereon. Aqueouspolyvinyl acetate dispersions, hereinafter also referred to as PVAcdispersions, are of particular significance in this regard, cf. A.Kullmann et al. in Arch. Acker-Pflanzenbau Bodenkd., 22(11), 713-19.Besides polyvinyl acetate, butadiene/styrene latex, a urea/formaldehydepolymer and a bitumen emulsion are described as useful binders. Thecorresponding stabilization of dune sand against the effects of rain isthe subject of an article by D. Gabriels et al. (Univ. Ghent, Belgium)in Soil Sci, 118(5), 332-8. In this publication, too, a binder systembased on polyvinyl acetate is included among the preferred binders. U.S.Pat. Nos. 4,072,020, 3,887,506, HU 11 654 and ZA 7501787 are mentionedas examples of the other works being carried out worldwide.

The list of requirements or functions to be fulfilled by correspondingstabilization of the earth's surface can be extremely diverse. Withoutany claim to completeness, some of the properties required in practiceare mentioned in the following: the material should be resistant atleast to pedestrian traffic, it should not be affected by the particulartemperatures prevailing, atmospheric humidity or rain (for the periodenvisaged) and should also be resistant to high wind speeds. Thematerial to be applied should be non-inflammable and should notrepresent a fire or explosion risk either in storage or during and afterits application. Its transport and application should not entail anyexceptional protective measures or the wearing of protective clothing.The cured polymer impregnation should not have any toxic effect ongerminating plants, on growing plants or on animals and should becolorless or transparent. Taking these and other requirements intoaccount, the present state of the art may be summarized as follows:

1. PVAc homopolymer dispersions are basically suitable as binders. Inthe absence of plasticizers, however, the cohesion of the soil layersimpregnated with PVAc homopolymer dispersions is so brittle that keyapplication requirements are not satisfied.

2. The deficiency mentioned in (1) can be eliminated by usingplasticizers capable of flow under normal conditions. In practice,dibutyl phthalate has proved to be a particularly effective plasticizer.Correspondingly plasticized PVAc homopolymers provide for firm cohesionalthough the plasticizer is non-degradable.

3. Internally plasticized polymer dispersions (polyvinyl acetateco-dibutyl maleate) provide for firm cohesion but are alsonon-degradable.

The teaching of earlier German patent application P 43 24 474.2 cited atthe beginning addresses the problem of providing PVAc homopolymerdispersions for the described application with plasticizers which, onthe one hand, meet the diverse requirement profile, but which on theother hand are biologically safe and, in particular, degradable. Theteaching in question is based on the knowledge that, basically, PVAchomopolymers are biologically safe and degradable even thoughdegradation of this polymer is comparatively slow. The relevantliterature is represented, for example, by H. Kastien et al. "Derquantitative mikrobiologische Abbau von Lackkunstharzen undPolymerdispersionen (The Quantitative Microbiological Degradation ofPaint-Grade Resins and Polymer Dispersions)" , Farbe+Lack, Vol. 98,7/1992, 505-8. According to the teaching of the earlier application, thefollowing selected classes of compounds are used as biologicallyacceptable plasticizers for PVAc dispersions: triesters of glycerol withlower aliphatic monocarboxylic acids, citric acid triesters with loweraliphatic monohydric alcohols and/or epoxidized triglycerides of atleast partly olefinically unsaturated fatty acids.

Particulars of the technical teaching according to earlier patentapplication P 43 24 474 can be found in its disclosure which is herebyincluded as part of the disclosure of the present invention.

Using the impregnating or solidifying compositions described in theearlier patent application cited above, it is possible optimally tostabilize the surface of the treated soil, for example in layerthicknesses of up to a few centimeters, so that the requirement profilementioned above is satisfied under normal conditions. Unfortunately,further investigations have shown that the surfaces thus stabilized canbe softened to a considerable extent by moist substrates/soils or byintensive contact with moisture, for example by heavy rain. Although thestabilizing effect generally returns after drying, i.e. does notdisappear completely, this is nevertheless a weakness in terms ofpractical application. The elimination of this weakness is the subjectof the teaching of the present invention. Accordingly, coating orimpregnating compositions for soil or sand are described in thefollowing which have a distinct stabilizing effect both on dry and onwet substrates and which retain their stabilizing effect both in dryconditions and in damp or wet conditions. The biological degradabilityand soil compatibility of the coating remain intact whatever theconditions.

DESCRIPTION OF THE INVENTION

Accordingly, the present invention relates to the use of fatty acids orfatty alcohols--which are solid at room temperature and/or which cure inthe presence of air--and/or at least substantially water-insolubleesters, ethers and/or salts thereof as degradable and biologicallycompatible stabilizers for increasing the water resistance of soilimpregnations based on polyvinyl acetate and comparable esters ofpolyvinyl alcohol with lower monocarboxylic acids.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly, the present invention proposes the following modificationto the described compositions: biologically safe and naturallydegradable auxiliaries which, by virtue of their at least predominantlyoleophilic molecular structure, are capable of distinctly increasing theresistance to water of the impregnating composition, even under extremeconditions, are introduced as an additional component into the soillayers to be stabilized. Nevertheless, the auxiliaries of the teachingaccording to the invention are accessible to natural degradationprocesses. In addition to the predominant oleophilic component, theirmolecular structure is distinguished by the presence of functionalgroups (hydroxyl groups, carboxyl groups, ether and/or ester groups)which are known as starting points for the simplified microbiologicaldegradation of such compounds or rather classes of compounds. Thedegradation rates of the auxiliaries used in accordance with theinvention are generally such that the desired protective effect of theimpregnating composition against excessive penetration of water can beguaranteed for the periods required in practice. The principle oftemporary soil stabilization described in detail in the earlierapplication cited above does of course provide for the simultaneousseeding of the soil layers to be stabilized with suitable plants and,hence, for increasing stabilization by natural plant growth as thetemporary stabilization provided by resin-based compositions inaccordance with the present invention disappears under the effect ofdegradation processes, more particularly bacterial degradationprocesses, in the soil.

The chemical structure of suitable and particularly preferred subclassesof the stabilizers according to the invention is discussed first in thefollowing. The preferred principles under which the stabilizers areintroduced and used in the impregnating composition and the layers ofsoil to be stabilized are described thereafter.

Fatty acids and fatty alcohols are known among experts to becorresponding compounds or mixtures of compounds which are distinguishedby a sufficiently long hydrocarbon chain in the molecule. This isresponsible for their predominantly oleophilic character despite thepresence of the hydrophilic functional groups. Accord- ingly, fattyacids and fatty alcohols corresponding to the definition according tothe invention are distinguished by hydrocarbon chains with at least 6and preferably at least 8 to 10 carbon atoms in the molecule. The upperlimit to the number of carbon atoms in the molecule is generally ataround 30 carbon atoms although this figure is by no means binding.Fatty acids of natural and/or synthetic origin--and the correspondingfatty alcohols--are generally mixtures which, on average, contain 10 to24 carbon atoms and, more particularly, around 12 to 22 carbon atoms inthe molecule. Reference is made in this regard to the literatureavailable to experts.

Another two elements of the molecular structure of the classes ofcompounds in question are used for their characterization: oleo-organiccompounds of the type in question may be aliphatically saturated or evenmonoolefinically and/or polyolefinically unsaturated. More particularly,numerous representatives of natural origin are distinguished by thepresence of more or less large quantities of such monoolefinicallyand/or polyolefinically unsaturated carboxylic acids with carbon chainlengths in the range mentioned, although if desired the synthesisprocesses typically in use today provide unsaturated representatives ofthe classes of compounds in question in addition to saturated types.

The second important characteristic is the chain structure of theparticular molecule. Natural fatty acids and fatty alcohols derived fromthem are characterized at least by far predominantly by their linearmolecular structure. Corresponding representatives with a more or lessheavily pronounced branching of the chain are known in syntheticchemistry in particular. Finally, the dependence of both rheology andbiological degradation behavior of these structural parameters of thefatty components are well known. With regard to rheology, both olefinicdouble bonds in the molecule and the branching of the chain lead to areduction in the melting points. Biological degradability is bestguaranteed among the linear representatives of the fatty components inquestion, corresponding representatives with an even number of carbonatoms, as present in the components based on natural materials, beingparticularly readily degradable. However, even limited chain branchingswith, in particular, occasional methyl substituents can still beeffectively degraded by biological degradation processes.

The desired degradation processes actually occurring within the contextof the teaching according to the invention are, in particular,corresponding aerobic mechanisms. It is known among experts that, underthese conditions, not only fatty acids, fatty alcohols and correspondingcomponents with ester groups undergo bacteriological degradation,corresponding ethers are also degraded under aerobic conditions--albeitgenerally with some delay.

These facts known per se among experts are intentionally discussed inthe description of the invention. So far as the teaching according tothe invention is concerned, the possibility of influencing the timerequired for the bacteriological degradation of the stabilizers used inaccordance with the invention by selecting certain molecular structuresof those stabilizers derives from these facts taking general specialistknowledge into consideration. Accordingly, it is thus indirectlypossible to regulate the time in which the moisture-repellinghydrophobic properties of the stabilizer are pronounced sufficientlystrongly to guarantee the required protective effect of the impregnatingcomposition in the soil.

Basically, any representatives of the class of stabilizers underdiscussion based on fatty alcohols, fatty acids, esters and/or ethersthereof and fatty acid salts are suitable for use in accordance with theinvention. The particular choice of specific representatives and theform in which they are applied are determined by the particularconditions prevailing and by individual requirements. Expert knowledgewill enable individually selected representatives of the classes ofstabilizers under discussion to be used in accordance with the inventionin the broadest sense.

Basically, it is preferred to use these stabilizers also in the form ofaqueous preparations and to introduce them into the soil in this form.Since the stabilizers as such are substantially insoluble in water,their use in the form of aqueous emulsions and/or dispersions is againthe optimal technical solution. As discussed in more detail hereinafter,the stabilizers may be used both in admixture with the impregnatingcompositions based on polyvinyl acetate and/or separately therefrom. Thestructure-dependent rheology of the classes of oleochemical compounds inquestion, the conditions for practical application and the requirementswhich the stabilizers used in accordance with the invention are expectedto satisfy in regard to soil impregnation enable individualrepresentatives of the compounds used in accordance with the inventionto be assigned to a number of subsidiary groups. Without any claim tocompleteness, the following observations may be made in this regard:

The stabilizers applied in the form of an aqueous emulsion or dispersionare generally required to have a minimum film forming temperature ofaround 0° to 15° C. and, more particularly, around 5° to 10° C. Onremoval of the aqueous phase either by sinking into the substrate or byevaporation, sufficiently continuous layers of the stabilizers areformed within the impregnation and/or on the surface thereof undernormal working conditions so that the desired protective effect againstthe excessive penetration of moisture can be achieved.

Suitable stabilizers may be present as solids or as liquid phases in thevicinity of this film forming temperature. Where the stabilizers usedare solid at the film forming temperature, it can be of advantage to useflow aids, more especially organic flow aids, which are preferablymiscible with the stabilizers and, at the same time, biologically safeand degradable. Suitable flow aids of this type are, for example,components based on alcohols, ethers and/or carboxylic acid esters whichare flowable and preferably show low volatility at tempera- tures of 5°to 15° C.

In one important embodiment, however, at least partly monoolefinicallyand/or polyolefinically unsaturated fatty acids, fatty alcohols and/orderivatives thereof with an ester and/or ether structure are used asstabilizers. Even in the case of linear fatty components of the type inquestion, the presence and number of the olefinic double bonds generallyguarantees adequate flowability at the application temperature of thesoil to be treated so that the formation of continuous hydrophobiclayers and hence the development of the required water-repellent effectare ensured. olefinically unsaturated stabilizers of the type inquestion afford an additional advantage, namely: as known per se,corresponding flowable fatty compounds dry under the effect ofatmospheric oxygen so that the originally liquid films are convertedinto solid films. Nevertheless, the biodegradability requirement remainsintact, cf. the above cited literature reference of Heinz Kastien et al.in "Farbe und Lack" 1992.

A particular feature for the formation of at least substantiallycontinuous oleochemical films lies in the following embodiment: bothunsaturated and monoolefinically and/or polyolefinically unsaturatedfatty acids can be converted by cations, more particularly polyvalentcations, into the corresponding salts which are generally distinguishedby modified rheological properties. Suitable and preferred polyvalentsalt-forming cations are, in particular, corresponding representativesof the second and/or third main group of the periodic system, moreparticularly calcium and/or aluminium. Salt formation may take placebefore or even after application of the stabilizers to the soil.Subsequent oxidative reaction and hence further stabilization can alsotake place in the case of corresponding salts with olefinicallyunsaturated components in the carboxylic acid groups.

Stabilizers of ester structure are of particular significance in thecontext of the teaching according to the invention, the defined fattyacid residues in a first class of compounds determining the esterstructure. The esters in question are, for example, full and/or partialesters of, in particular, at least partly olefinically unsaturated fattyacids with polyhydric alcohols. Preferred esters are derived from lowerpolyhydric alcohols containing in particular 2 to 6 hydroxyl groups andpreferably up to 6 carbon atoms. Corresponding glycerides or partialglycerides of the fatty acids and/or their oligomers can be particularlyinteresting representatives for the purposes of the teaching accordingto the invention.

Oils and/or fats based on natural materials are mentioned purely by wayof example in this connection. Corresponding oils and/or fats are knownto accumulate as triglycerides of fatty acids or fatty acid mixtureswith at least partly olefinically unsaturated fatty acid components inthe triglyceride. Depending on the structure and concentration of theunsaturated fatty acid residues, oils and/or fats of the type inquestion are suitable for oxidative curing through three-dimensionalcrosslinking. Wide scale use is made of this in practice, cf. forexample the field of paint raw materials where, for example, oxidativelycuring oils of natural origin based on linseed oil have long been widelyused. Corresponding stabilizers of natural origin can be importantcomponents for the application according to the invention. They may beused with or without curing components which generally accelerate theformation of a three dimensionally crosslinked paint film. Relevantexpert knowledge may be applied in this connection.

Another preferred class of ester-based stabilizers may be defined asoligo- or polyesters of fatty acids and/or fatty alcohols andpolyfunctional reactants from the classes of oligo- or polycarboxylicacids and/or oligo- or polyalcohols. Examples of such stabilizers arethe known polyesters of the alkyd resin type and also polyvinyl alcohololigomers and polymers esterified with fatty acid residues and(meth)acrylate oligomers and/or polymers esterified with optionallyolefinically unsaturated fatty alcohol residues. An important criteriondetermining the choice of these stabilizers can again be the question ofsufficiently complete degradability by natural degradation processes inthe soil not only of individual components of the ester or polyesterstructure. More particularly, the choice of stabilizer for theapplication according to the invention may be co-determined by thedegradability of the primary components of the starting molecule, forexample in the course of an ester hydrolysis.

In the context of the alkyd resins discussed in the foregoing as asuitable class of stabilizers, it can be of advantage to use selectedcompounds of this type which are at least largely based on naturalmaterials. It is known that alkyd resins include polyesters ofpolycarboxylic acids, polyols and monofunctional alcohols and/orcarboxylic acids. Oxidatively reactive alkyd resins are known commercialproducts; to this extent, reference may be made to general expertknowledge. They may be used, for example, as raw materials forair-drying paints. Known commercial products are also made up inparticular in the form of aqueous dispersions which contain theself-drying alkyd resins in the form of a finely dispersed resin in acontinuous aqueous liquid phase. Air-reactive aqueous alkyd resindispersions of this type are particularly suitable starting materialsfor the purposes of the invention.

The oxidative reactivity of such alkyd resin derivatives is generallyattributable to a content of olefinically unsaturated substituents inthe alkyd resin polyester molecule. Corresponding olefinicallyunsaturated reactive elements may be introduced into the alkyd resinmolecule in known manner by incorporation of unsaturated alcohols and/orunsaturated carboxylic acids. Representatives of the alkyd resinsdiscussed in the foregoing which are at least largely based on naturalmaterials can be of particular interest in this regard and in connectionwith the teaching according to the invention. Thus, monocarboxylic acidsand/or monohydric alcohols of natural origin may be used to derivatizethe alkyd resins. Where dicarboxylic acids and at least trihydricalcohols are used in combination with monobasic carboxylic acids and,optionally, other diols, it is possible for example to obtaincorresponding monocarboxylic-acid-derivatized alkyd resins which can bemade to react or crosslink by oxidation through the use of at leastpartly mono- and/or polyolefinically unsaturated monocarboxylic acids.An oxidatively reactive alkyd resin modified with olefinicallyunsaturated alcohols can also be prepared in known manner by reversingthe functionalities.

Alkyd resins based on natural materials of the particularly preferredtype according to the invention are based on glycerol as thetrifunctional polyol component and fatty acids of natural origin as themonofunctional carboxylic acid component. The monofunctional reactantsare used on average in such quantities as to allow the required reactionwith dicarboxylic acids which, in one preferred embodiment, are in turndegradable in natural degradation processes. Corresponding modifiedalkyd resins based at least largely on natural materials are thendistinguished, for example, by the fact that more than 50% by weight andpreferably from 60 to 70% by weight of the alkyd resin consists ofcomponents based on natural materials, more particularly glycerol andmonofunctional fatty acids, and for the rest of dicarboxylic acids and,optionally, additional diol components in the polymer molecule.

The stabilizers according to the invention may be introduced into thesoil by, in particular, two methods, which, if desired, may even becombined with one another. In a first embodiment, the impregnatingcomposition based on the polyvinyl ester preparations is introduced in afirst step while the stabilizer preparation is separately applied orintroduced thereafter. However, the two treatment preparations may alsobe introduced together into the soil. To this end, the generally aqueouspreparations of the impregnating composition and the stabilizers mayinitially be mixed together and then applied to the soil. These twointroduction mechanisms may be combined with one another. Thetheoretically possible other variant where the stabilizer is initiallyintroduced and the impregnating composition subsequently introducedgenerally gives unsatisfactory results.

The quantity of stabilizers to be used in each individual case isinfluenced by a number of factors. Minimum quantities of at least about50 g/m² of surface area to be treated and preferably quantities of atleast about 100 g/m² are generally desirable and suitable forestablishing durable increases in the strength of thepolyvinyl-acetate-based impregnating composition. The lower limitsmentioned apply to the water-free stabilizers or stabilizer mixturesfree from optional flow aids. Quantities of stabilizer of up to 400 g/m²of surface area to be treated may be desirable in special cases althoughsatisfactory results are generally achieved with quantities ofstabilizer of around 150 to 250 g/m².

The quantity ratios of stabilizer on the one hand and impregnatingcomposition on the other hand (based once again on the water-freemixtures of pure useful materials) may vary within relatively widelimits. For example, quantity ratios of the impregnating composition,more particularly based on PVAc, to the stabilizers (water-free usefulmaterials) of about 5:1 to 1:5 are suitable, corresponding ratios of 1:3to 2:1 being preferred. Substantially equal quantities of impregnatingcomposition and stabilizer have proved to be useful in manyapplications.

The depth of penetration of the impregnation into the soil can beinfluenced to a certain extent by sufficiently diluting the componentsin the aqueous preparations applied. The respective aqueous preparationsmay be applied by hand, for example with a watering can, although--on anindustrial scale--they are preferably applied by spray nozzles. Unlessthe two components in question are applied together or simultaneously ina single operation, it can be useful to allow a certain time, usually afew hours or even longer, to elapse between the first application of theimpregnating composition and the second application of the aqueousstabilizer preparations defined in accordance with the invention.

Particulars of the characteristics of the impregnating composition basedon selected polyvinyl ester dispersions can be found in applicants'earlier German patent application P 43 24 474.2. The followingadditional observations are made over and above the disclosure of thatpatent application:

Polyvinyl acetate is particularly suitable as the polymeric binder ofthe impregnating composition. However, the teaching according to theinvention is not confined to polyvinyl acetate. Other polymers of vinylalcohol with lower monocarboxylic acids, more particularly with up to 4or 5 carbon atoms in the carboxylic acid residue, may also be used.Besides polyvinyl acetate, polyvinyl propionate and aqueous preparationsthereof are particularly important. Both homopolymers and copolymers ofthe polyvinyl esters mentioned may be used in practice.

In another modification of the teaching according to the invention, animportant constituent of the impregna- ting composition may be derivedfrom the group of vinyl ester copolymers. Copolymers of lower vinylesters of the vinyl acetate and/or propionate type with vinyl esters ofhigher monobasic carboxylic acids are particularly suitable vinyl estercopolymers. Preferred representatives of this group of copolymers arethe vinyl esters of, in particular, saturated monocarboxylic acidscontaining at least 8 and preferably at least 10 carbon atoms,particular significance being attributed to monocarboxylic acidscontaining 10 to 16 carbon atoms. An important representative of suchcopolymers for many reasons is, for example, a polyvinyl acetateco-laurate.

To complete the disclosure of the present invention, basic principles ofthe impregnating composition based on polyvinyl acetate are described inthe following with reference to the earlier application cited above. Thecorresponding observations may also be applied to the above-describedextended possibility of forming the polymer compounds in theimpregnating composition.

Plasticizers are generally added to the aqueous polyvinyl acetatedispersions to improve the mechanical load-bearing capacity of theimpregnated soil. The preferred biodegradable plasticizers are triestersof glycerol with lower aliphatic monocarboxylic acids, citric acidtriesters with lower aliphatic monohydric alcohols and/or epoxidizedtriglycerides of at least partly olefinically unsaturated fatty acids.These plasticizers are added to the aqueous polyvinyl acetatedispersions in small quantities, normally in quantities of around 1 to15% by weight and preferably in quantities of around 3 to 10% by weight,based on an approximately 50% by weight aqueous polyvinyl acetatedispersion. Preferred glycerol triesters of aliphatic monocarboxylicacids contain monocarboxylic acid residues with 2 to 6 and preferably 2to 4 carbon atoms in the molecule. Triacetin is particularly importantas a plasticizer. Suitable citric acid triesters contain residues ofaliphatic monohydric alcohols containing 2 to 6 carbon atoms and, moreparticularly, 2 to 4 carbon atoms. Suitable representatives from thisgroup are citric acid triesters which contain the citric acid residue assuch and also corresponding derivatives of citric acid in the form ofthe variant acylated at the hydroxyl group.

It is characteristic of the plasticizers in the impregnating compositionthat even comparatively small quantities guarantee sufficientflexibilization of the solidified layer.

A special aspect regarding the need to add a plasticizer can apply incases where the vinyl ester copoly- mers mentioned above containinglower vinyl esters of the vinyl acetate and/or propionate type togetherwith vinyl esters of higher monofunctional carboxylic acids, moreparticularly a fatty acid, in the molecule are used. Further studiesconducted by applicants have shown that impregnating compositions basedon these vinyl ester copolymers meet the two requirements ofsufficiently plasticized impregnation and biological degradability, evenwithout the addition of plasticizers. Accordingly, there is no need intheir case to use plasticizers of the type known from the prior art anddescribed in applicants' earlier German patent application P 43 24 474.2cited at the beginning.

The preferred measure that other additives of the selected aqueousimpregnating and stabilizing compositions should be biologicallydegradable and hence biologically safe also applies to the teachingaccording to the invention. According to the invention, biodegradableprotective colloids in particular are used to stabilize the aqueouspreparations. Suitable protective colloids are, for example, polyvinylalcohol and also starch and/or water-soluble starch derivatives (thestarch may even be subjected to a partial reduction in molecularweight). However, the incorporation of readily degradable naturalmaterials of the starch type and/or the water-soluble starch derivativetype does endanger the stability of the film to erosion by rain and,hence, involves the danger of over-rapid degradation of the film. Theuse of the stabilizers in accordance with the invention can provideimportant assistance in this regard. The quantities in which theprotective colloids or emulsifiers are used are typically at most about5% by weight and, more particularly, in the range from about 0.5 to 3%by weight, based on the water-free useful material of the aqueousemulsion or dispersion used.

The technical elements developed in the relevant prior art for theformation of corresponding surface films may also be utilized in thecontext of the teaching according to the invention. For example,reference is made in this regard to the use of growth-promoting activesubstances, more particularly fertilizing auxiliaries, and/or to the useof preferably fine-particle solids, more particularly in the aqueouspreparation of the impregnating composition. In the last-mentioned case,it is known that the prior art provides in particular for the use offine-particle solids based on natural materials, such as sawdust, strawparticles, cereal husks, coconut and/or flax fibers and the like, inorder in this way to ensure the formation of local openings for furtherpromoting plant growth without endangering the overall cohesion of thesolidified layer.

The use of small quantities of surface-active components, moreparticularly in the aqueous preparations of the impregnating compositionand/or stabilizers, can be desirable. Particularly suitablesurface-active components are those of the o/w type which, in thepreferred embodiment, are also distinguished by biological compatibilityand, more particularly, by biological degradability. Correspondingsurfactants based on alkyl polyglycosides (APG) are particularlyimportant in this regard. By using components such as these, it ispossible on the one hand to facilitate stabilization, more particularlythe stabilization of stabilizer components in aqueous preparations (forexample the stabilization of linseed oil as an aqueous dispersion) and,on the other hand, to promote wetting of the soil to be stabilized. Ameasure such as this is of practical significance, for example, in thestabilization of overdried areas of sand. Relevant expert knowledge maybe applied in regard to the type and quantity of particularsurface-active agents used.

The soil-stabilizing aqueous preparations may be applied in known mannerat the same time as plant seeds. However, the corresponding treatment ofthe soil may also be carried out independently of stabilization beforeor after application of--in particular--the aqueous impregnatingcomposition defined in accordance with the invention.

Field trials with the auxiliaries described in accordance with theinvention have shown that not only can the required stabilization ofsoil be achieved and maintained over a considerable period of at leastseveral weeks without affecting the germination processes and resultingplant growth, another often desirable effect has also been observed:water retention in areas of soil treated in accordance with theinvention is distinctly increased in relation to adjacent untreatedareas of soil. It is clear that there are important advantages here,more especially for the stabilization and grassing of soil in aridregions and/or under comparatively hot climatic conditions.

The invention proposes another possible modification for enhancing thiseffect: the chemistry of natural materials, synthetic chemistry and/orsemisynthetic chemistry have developed a plurality of polymer componentswhich are distinguished by an extreme water absorption capacity and by ahigh retention capacity for the water absorbed. Corresponding materialsare widely used as socalled "super-slurpers" in various fields ofapplication, more particularly in the field of hygiene. Now, suitablepreparations of such water-binding polymers may also be used inaccordance with the invention for treating surface layers of soil andhence for promoting plant growth and, at the same time, limit thequantity and/or frequency of artificial watering of the soil plantedwith seeds, for example grass seeds. These water-binding semisyntheticor fully synthetic polymers may be introduced into the soil before it istreated with the impregnating compositions described in accordance withthe invention, although they may also be combined with at least part ofthe adhesive-like impregnating composition. Information on the chemicalcharacteristics of these water-binding auxiliaries can be found in therelevant specialist literature on auxiliaries of the type in question.Growth-promoting auxiliaries may also be used in accordance with theteaching of the present invention.

EXAMPLES Example 1

In a first series of tests, coarse builder's sand is stabilized as aworking model. The builder's sand is placed in trays measuring 33×24 cm.The layer thickness of the sand is about 2 to 3 cm.

The binders used are based on an aqueous polyvinyl acetate dispersion(first test group) and on a corresponding aqueous dispersion of a vinylacetate/vinyl laurate copolymer--ratio by weight of VAc to VL approx.3:1 --(second test group) which have been diluted with water to a solidscontent of 10% by weight. Quantities of 2,000 g/m² of these dispersionsare uniformly sprayed, sprinkled or brushed onto the surface of thesand. The dispersions of the first test group contain triacetin asplasticizer; the dispersions of the second test group areplasticizer-free.

After an intermediate drying time of around 24 hours, thestabilizer--also in the form of an aqueous preparation diluted to 10% byweight--is applied in a quantity of 2,000 g/m². Accordingly, thequantity of polymer applied both as PVAc or copolymer and as stabilizeramounts to 200 g/m².

In alternative tests, a 20% by weight aqueous dispersion containing 10%by weight of PVAc and 10% by weight of the stabilizer is used to treatthe builder's sand in the trays. The quantity applied again amounts to2,000 g/m².

A commercial alkyd resin dispersion ("Jagalyd WE 57", a product of E.JAger, Dusseldorf) is used as stabilizer in accordance with the teachingof the invention.

The sand samples treated in accordance with the invention in the traysare dried and evaluated or subjected to a watering cycle and thenmeasured for wet stability. In addition, the layer thickness of thesolidified sand layers is determined.

The particulars of the treatment steps carried out and theaftertreatment or evaluation of the test samples can be found in Table 1below. The following symbols were used for the strength evaluation ofthe treated sand layer:

F++=hard surface

F+=surface yields, but solidified

F-=surface partly solidified

F--=surface slightly solidified

                                      TABLE 1                                     __________________________________________________________________________    Comparison Examples                                                           Impregnating agent                                                                       PVAc   PVAc/VL                                                     __________________________________________________________________________    Plasticizer                                                                              5% Triacetin                                                       Stabilizer (alkyd resin) Jagalyd WE 57                                        Concentration applied                                                                    10     10     10                                                   in % by weight                                                                Layer thickness of sand                                                                  2-3 cm 2-3 cm 2-3 cm                                               Strength after drying                                                                    F++    F+     F++                                                  Thickness of the solidi-                                                                 1.6 cm        0.74 cm                                              fied layer                                                                    1st Watering                                                                  Appearance in the moist                                                                  F+     F+     F-                                                   state                                                                         Appearance after drying                                                                  F++    F++    F-                                                   for 24 h                                                                      Appearance after                                                                         F--    F--    F--                                                  artificial watering for                                                       1 week                                                                        Evaluation in the                                                             moist state                                                                   __________________________________________________________________________    Examples according to the invention                                           Impregnating agent                                                                       PVAc   PVAc   PVAc   PVAc/VL                                                                              PVAc/VL                                __________________________________________________________________________    Plasticizer                                                                              5% Triacetin                                                                         5% Triacetin                                                                         5% Triacetin                                         Stabilizer (alkyd resin)                                                                 Jagalyd WE 57                                                                        Jagalyd WE 57                                                                        Jagalyd WE 57                                                                        Jagalyd WE 57                                                                        Jagalyd WE 57                          Application                                                                              Separate                                                                             Separate                                                                             Separate                                                                             Separate                                                                             Together                               Concentration applied                                                                    10     10     10     10     10                                     in % by weight                                                                Ratio (PVAc/stabil.)                                                                     1:1    0.2:0.8                                                                              0.8:0.2                                                                              1:1    1:1                                    Layer thickness of sand                                                                  2-3 cm 2-3 cm 2-3 cm 2-3 cm 2-3 cm                                 Strength after drying                                                                    F++    F+     F-     F++    F++                                    Thickness of the solidi-                                                                 2.0-2.5 cm                                                                           1.8-2.0 cm                                                                           0.5-0.7 cm                                                                           2.0 cm 2.0 cm                                 fied layer                                                                    1st Watering                                                                  Appearance in the moist                                                                  F++    F+     F+     F++    F++                                    state                                                                         Appearance after drying                                                                  F++    F++    F+     F++    F++                                    for 24 h                                                                      Appearance after                                                                         F++    F++    F--    F++    F++                                    artificial watering for                                                       one week                                                                      Evaluation in the moist                                                       state                                                                         __________________________________________________________________________

In another series of tests, trays comparable to those described abovewere not artificially watered in the laboratory, but instead were leftoutdoors at applicants' headquarters for the months of March and April,1994 and then evaluated.

The results of this evaluation are set out in Table 2 below.

                                      TABLE 2                                     __________________________________________________________________________    Impregnating agent                                                                          PVAc    PVAc    PVAc                                            __________________________________________________________________________    Plasticizer   5% Triacetin                                                                          5% Triacetin                                                                          5% Triacetin                                    Stabilizer (alkyd resin)                                                                    Jagalyd WE 57                                                                         Jagalyd WE 57                                                                         Jagalyd WE 57                                   Application   Separate                                                                              Separate                                                                              Separate                                        Concentration applied                                                                       5       10      30                                              in % by weight                                                                Ratio         1:1     1:1     1:1                                             Layer thickness of sand                                                                     2-3 cm  2-3 cm  2-3 cm                                          Strength after drying                                                                       F++     F++     F+                                              Thickness of the solidified layer                                                           2.0-2.5 cm                                                                            2.1-2.5 cm                                                                            0.3-0.6 cm                                      Storage outdoors for 1 day                                                    Appearance in the moist state                                                               --      F++     --                                              Appearance after 1 week                                                                     F++     F++     F--                                             outdoors with rain                                                            Appearance after 1 month                                                                    F++     F++     F--                                             outdoors with rain                                                            Appearance after 2 months                                                                           F++                                                     outdoors with rain                                                            __________________________________________________________________________

Comparison of the last column of Table 2 with the preceding columnsshows that, where the surface penetration of the impregnatingcompositions is inadequate, unsatisfactory stabilization is obtained. Inthe case illustrated, penetration of the impregnating composition andthe associated stabilizer was inadequate because of their excessiveconcentration in the aqueous treatment formulations.

To evaluate the effect of different quantities and concentrationsapplied, the tests described above were repeated in trays with a sandlayer thickness of around 10 cm. The results are set out in Table 3below.

                                      TABLE 3                                     __________________________________________________________________________    Impregnating agent                                                                          PVAc    PVAc    PVAc                                            __________________________________________________________________________    Plasticizer   5% Triacetin                                                                          5% Triacetin                                                                          5% Triacetin                                    Stabilizer (alkyd resin)                                                                    Jagalyd WE 57                                                                         Jagalyd WE 57                                                                         Jagalyd WE 57                                   Application   Together                                                                              Together                                                                              Together                                        Concentration applied                                                                       5       10      30                                              in % by weight                                                                Ratio         1:1     1:1     1:1                                             Layer thickness of sand                                                                     10 cm   10 cm   11 cm                                           Strength after drying                                                                       F++     F++     F+                                              Thickness of the solidified layer                                                           2.0-2.1 cm                                                                            2.1-2.4 cm                                                                            0.8-1.0 cm                                      Storage outdoors for 1 day                                                    Appearance in the moist state                                                               F++     F++     F-                                              __________________________________________________________________________

Example 2

The results of the laboratory tests of Example 1 were investigated infurther tests.

An earth wall with an inclination of approximately 45° and a height of 5m is coated in accordance with the invention in 2 m wide segments withthe aqueous stabil- izing dispersions. To this end, the liquid isintroduced into a pressure vessel and sprayed through a flat nozzleunder a container pressure of around 8 bar. Application lasted about 3to 5 minutes.

At the time of application, the earth wall was slightly moist (rain onthe previous day). The weather was dry during application and on thefollowing day. To test plant growth, both the segments to be treated andthe area around these segments were sown with natural meadow seeds.

Seven test fields were treated and evaluated in accordance with thefollowing particulars under "test numbers 1 to 7". The test details wereas follows.

    ______________________________________                                        Test number: 1                                                                ______________________________________                                        Stabilizing material  PVAc                                                    Method of application Spraying                                                Form as supplied      57.5% by wt.*                                           Application form      10% by wt.                                              Dilution of the form  1:5.75                                                  as supplied with water                                                        in a ratio of                                                                 Area coated           10 m.sup.2                                              Quantity of application                                                                             20 l                                                    form used                                                                     Density of coating with                                                                             200 g/m.sup.2                                           solid                                                                         Aftertreatment        None                                                    Results immediately   Flexible,                                               after application     coherent                                                ______________________________________                                        Test number: 2                                                                ______________________________________                                        Stabilizing material                                                                          PVAc         Alkyd resin                                      Method of application                                                                         Spraying,    Spraying after                                                   separate     waiting for 3 h                                  Form as supplied                                                                              57.5% by wt. 65% by wt.                                       Application form                                                                              10% by wt.   10% by wt.                                       Dilution of the form                                                                          1:5.75       1:6.5                                            as supplied with water                                                        in a ratio of                                                                 Area coated     10 m.sup.2   10 m.sup.2                                       Quantity of application                                                                       20 l         20 l                                             form used                                                                     Density of coating with                                                                       200 g/m.sup.2                                                                              200 g/m.sup.2                                    solid                                                                         Aftertreatment  None         None                                             Results immediately                                                                           Flexible,    Flexible,                                        after application                                                                             coherent     coherent                                         ______________________________________                                        Test Number: 3                                                                ______________________________________                                        Stabilizing material                                                                          PVAc         Alkyd resin                                      Method of application                                                                         mixture sprayed                                               Form as supplied                                                                              57.5% by wt. 65% by wt.                                       Application form                                                                              10% by wt.   10% by wt.                                       Dilution of the form                                                                          1:2.9        1:3.3                                            as supplied with water                                                        in a ratio of                                                                 Area coated     10 m.sup.2   10 m.sup.2                                       Quantity of application                                                                       20 l         20 l                                             form used                                                                     Density of coating with                                                                       200 g/m.sup.2                                                                              200 g/m.sup.2                                    solid                                                                         Aftertreatment  None         None                                             Results immediately                                                                           Flexible,    Flexible,                                        after application                                                                             coherent     coherent                                         ______________________________________                                        Test number: 4                                                                ______________________________________                                        Stabilizing material                                                                          PVAc         Alkyd resin                                      Method of application                                                                         Mixture sprayed                                               Form as supplied                                                                              57.5% by wt. 65% by wt.                                       Application form                                                                              10% by wt.   10% by wt.                                       Dilution of the form                                                                          1:2.9        1:3.3                                            as supplied with water                                                        in a ratio of                                                                 Area coated     10 m.sup.2   10 m.sup.2                                       Quantity of application                                                                       20 l         20 l                                             form used                                                                     Density of coating with                                                                       200 g/m.sup.2                                                                              200 g/m.sup.2                                    solid                                                                         Aftertreatment  Watered after 3 h                                                             with 2 l/m.sup.2                                              Results immediately                                                                           Soft, flexible, coherent                                      after application                                                             ______________________________________                                        Test number: 5                                                                ______________________________________                                        Stabilizing material                                                                            Commercial product based                                                      oligobutadiene                                              Method of application                                                                           Spraying                                                    Form as supplied  35% by wt.                                                  Application form  3.5% by wt.                                                 Dilution of the form                                                                            1:10                                                        as supplied with water                                                        in a ratio of                                                                 Area coated       10 m.sup.2                                                  Quantity of application                                                                         10 l                                                        form used                                                                     Density of coating with                                                                         35 g/m.sup.2                                                solid                                                                         Aftertreatment    None                                                        Results immediately                                                                             No Cohesion                                                 after application                                                             ______________________________________                                        Test number: 6                                                                ______________________________________                                        Stabilizing material PVAc                                                     Method of application                                                                              By watering can                                          Form as supplied     57.5% by wt.                                             Application form     10% by wt.                                               Dilution of the form 1:5.75                                                   as supplied with water                                                        in a ratio of                                                                 Area coated          10 m.sup.2                                               Quantity of application                                                                            20 l                                                     form used                                                                     Density of coating with                                                                            200 g/m.sup.2                                            solid                                                                         Aftertreatment       None                                                     Results immediately  Soft, flexible,                                          after application    coherent                                                 ______________________________________                                        Test number: 7                                                                ______________________________________                                        Stabilizing material                                                                           PVAc         Alkyd resin                                     Method of application                                                                          Mixture sprayed                                              Form as supplied 57.5% by wt. 65% by wt.                                      Application form 10% by wt.   10% by wt.                                      Dilution of the form                                                                           1:2.9        1:3.3                                           as supplied with water                                                        in a ratio of                                                                 Area coated      10 m.sup.2   10 m.sup.2                                      Quantity of application                                                                        10 l         10 l                                            form used                                                                     Density of coating with                                                                        100 g/m.sup.2                                                                              100 g/m.sup.2                                   solid                                                                         Aftertreatment   None                                                         Results immediately                                                                            Flexible, coherent                                           after application                                                             ______________________________________                                         *% by wt. = % by weight                                                  

All the test fields except for field 5 showed distinct stabilization ofthe soil surface 3 hours after application. In field 5(oligobutadiene-based treatment preparation), no significant soilstabilization was discernible.

In further tests, the test fields thus treated and the adjoining areaswere regularly observed and artificially watered in view of the hot anddry weather conditions. The particulars were as follows:

Weather since the beginning of the test in the middle June, 1994: hotand dry. No visible cracking through drying out of the test fields.

10 Days after application, each field is watered by pump for 5 minutesat an outside temperature of 28° C. 24.6 Liters of water per M 2 weresprayed on under a pump pressure of around 25 bar.

The evaluation of test fields 1 to 7 was as follows:

Field 1:

Water absorption very good, serious sliding in the upper quarter afterwatering

Field 2:

Water absorption very good, strength remained intact, no cracks, nosliding

Field 3:

Water absorption very good, strength remained intact, no cracks, nosliding

Field 4:

Water absorption very good, cracks formed after watering for 3 minutes,risk of sliding

Field 5:

Water absorption only moderate, drained off the surface, cracks formedafter only brief watering, flooding, watering terminated after 3 mins.

Field 6:

Water absorption very good, strength remained intact, no cracks, nosliding

Field 7:

Water absorption very good, strength remained intact, no cracks, nosliding

4.5 Hours after watering, the condition of the test fields isre-inspected and evaluated. The results were as follows:

Field 1:

Surface only a thin crust, cracked

Field 2:

Surface thin crust, condition good, slightly cracked

Field 3:

As field 2

Field 4:

Surface slightly more stable, no further cracks or sliding sincewatering

Field 5:

Hardly anything to be seen or felt of the surface treatment

Field 6:

Surface hard, but not cracked, condition very good

Field 7:

As field 6

Despite the intense heat, none of the test fields had dried out, butinstead still had a good moisture level. The untreated areas adjacentthe test fields had become very dry over the same period. The previouslysown grass seeds had not been washed away from any of the treated testfields.

3 Weeks after the beginning of the test (several heavy showers of rainhad fallen on the test fields over this period), the grass seeds hadgerminated and plant growth appeared to be unimpeded by comparison withthe untreated, adjacent seeded areas.

Example 3

Further tests with PVAc as impregnating agent, but with otherstabilizers were carried out in accordance with the teaching of theinvention by the same method as in Example 1. The formulations used andthe results obtained are set out in Table 4 below.

The commercial stabilizer "JAGALYD WE 156" (a product of E. JAGER,Dusseldorf) was used as stabilizer. This product is a water-emulsified,drying and pollutant-free binder based on natural/synthetic materialswhich may be used, for example, for water-dilutable wood protectionvarnishes. In the other two tests of Table 4, linseed oil was used asthe stabilizer according to the invention. In one test, the linseed oilwas used in the form of a 10% aqueous emulsion (APG as emulsifier) and,in the other test, was applied as such to the sand surface to bestabilized.

In all the tests, the impregnating agent was an aqueous PVAC dispersioncontaining 5% by weight of triacetin which was applied to the sandsurfaces to be stabilized separately from the stabilizer according tothe invention in a first process step.

Particulars of the formulations used and the test results obtained afterartificial watering are set out in Table 4 below. The evaluation of thestrength values (F) corresponds to the symbols identified in Example 1.

                                      TABLE 3                                     __________________________________________________________________________    Impregnating agent                                                                          PVAc    PVAc    PVAc                                            __________________________________________________________________________    Plasticizer   5% Triacetin                                                                          5% Triacetin                                                                          5% Triacetin                                    Coverage of solids 1                                                                        7.7 g/380 cm.sup.2                                                                    7.7 g/380 cm.sup.2                                                                    7.7 g/380 cm.sup.2                              Concentration applied                                                                       10%     10%     10%                                             Stabilizer    Jagalyd WE 156                                                                        Linseed oil                                                                           Linseed oil                                     Coverage of solids 2                                                                        7.7 g/380 cm.sup.2                                                                    7.7 g/380 cm.sup.2                                                                    7.7 g/380 cm.sup.2                              Concentration applied +                                                                     10%     10%     --                                              APG for emulsification                                                                      --      1.50%   --                                              Layer thickness of sand or soil                                                             3 cm    3 cm    3 cm                                            Application   Separate                                                                              Separate                                                                              Separate                                        Strength after drying                                                                       F+      F+      F+                                              Thickness of the solidified layer                                                           1.8 cm  1.0 cm  1.4 cm                                          First artificial watering                                                                   1.5 1/m.sup.2                                                                         1.5 1/m.sup.2                                                                         1.5 l/m.sup.2                                   Strength      F+      F-      F+                                              Second artificial watering                                                                  3.0 1/m.sup.2                                                                         3.0 1/m.sup.2                                                                         3.0 l/m.sup.2                                   Strength      F+      F-      F+                                              Third artificial watering                                                                   1.5 1/m.sup.2                                                                         1.5 1/m.sup.2                                                                         1.5 l/m.sup.2                                   Strength      F++     F++     F++                                             Precipitation on 6th day                                                                    12 1/m.sup.2                                                                          12 1/m.sup.2                                                                          12 l/m.sup.2                                    1 week        F+      F+      F+                                              Strength                                                                      __________________________________________________________________________

What is claimed is:
 1. The process of increasing the water resistance ofsoil impregnated with esters of polyvinyl alcohol and monocarboxylicacids selected from the group consisting of C₁ -C₅ monocarboxylic acidsand C₈ -C₁₆, monocarboxylic acids and mixtures thereof comprising addingto said soil a stabilizer selected from the group consisting of mono- orpolyolefinically unsaturated fatty acids, fatty alcohols, and water-insoluble esters, ethers and salts thereof.
 2. A process as in claim 1wherein said fatty acids and fatty alcohols contain 6 to 30 carbonatoms.
 3. A process as in claim 1 including adding to said soilimpregnated with said esters of polyvinyl alcohol a plasticizer selectedfrom the group consisting of triesters of glycerol and lower aliphaticC₂₋₄, monocarboxylic acids, citric acid triesters and aliphatic C₂ -C₆monohydric alcohols, and epoxidized triglycerides of at least partlyolefinically unsaturated fatty acids.
 4. A process as in claim 1 whereinsaid unsaturated fatty acids are present as calcium or aluminum saltsthereof.
 5. A process as in claim 1 wherein said stabilizer is appliedto said soil in admixture with said esters of polyvinyl alcohol.
 6. Aprocess as in claim 1 wherein said stabilizer is applied to said soil inthe form of an aqueous dispersion or emulsion.
 7. A process as in claim1 wherein said stabilizer is a solid at a temperature of 5° C. to 15° C.and is applied to said soil in the presence of an organic flow aid.
 8. Aprocess as in claim 7 wherein said flow aid is selected from the groupconsisting of alcohols, ethers and carboxylic acid esters which flow ata temperature of 5° C. to 15° C.
 9. A process as in claim 1 whereinstabilizer consisting of said esters is an ester of at least partlyolefinically unsaturated fatty acids and alcohols containing 2 to 6hydroxyl groups and up to 6 carbon atoms.
 10. A process as in claim 1wherein said stabilizer is selected from the group consisting of apolyester of an alkyd resin, a polyvinyl alcohol oligomer and polymeresterified with fatty acid residues and (meth)acrylate oligomersesterified with optionally olefinically unsaturated fatty alcoholresidues.
 11. A process as in claim 1 wherein said stabilizer is derivedfrom natural materials.
 12. A process as in claim 1 wherein said estersof polyvinyl alcohol are selected from the group consisting of polyvinylacetate, polyvinyl propionate, and copolymers thereof with vinyl estersof C₈ -C₁₆ fatty acids.
 13. A process as in claim 1 wherein said estersof polyvinyl alcohol and said stabilizer are present in a weight ratioof 5:1 to 1:5 on a solids basis.
 14. A process as in claim 1 includingadding to said stabilizer a film-forming agent having a minimumfilm-forming temperature of from 0° C. to 15° C.
 15. A process as inclaim 1 wherein said esters of polyvinyl alcohol and said stabilizer areapplied to said soil in a quantity of about 50 g/m² to about 250 g/m² ofsoil area.
 16. A process as in claim 1 including adding plant seeds tosaid soil.